Xinxiang Ceramic Mug Manufacturer, spray glazing is a surface treatment technique used in the production of ceramic mugs. A spray gun is used to atomize the glaze into tiny particles, which are then evenly sprayed onto the surface of the ceramic blank. Glaze is a glass-like coating that, when fired, gives ceramics smooth, waterproof, and wear-resistant properties, while also serving a decorative purpose. Spray glazing is suitable for complex shapes (such as unconventional mugs) or ceramic mugs that require fine gradation effects. Compared with traditional dip glazing, it allows for more flexible control of glaze thickness and coverage.

1. Spray glazing operation process
The spray glazing process is more advanced than dip glazing. Currently, ceramic mug factories commonly use two types of spray glazing processes: manual spray glazing and automatic spray glazing. Manual spraying requires a spray gun and air pump. The technician holds the spray gun, keeping it 20-30 cm away from the mug, with an air pressure of 0.3-0.5 MPA, and moves the spray gun at a constant speed, first covering the edges and recesses, then spraying the entire surface to ensure an even glaze layer. Complex areas (such as the inside of the mug handle) need to be sprayed repeatedly. Automatic assembly line operation: Place the ceramic mug blank upside down on the rack and send it to the conveyor belt. When the rack moves the ceramic mug under the spray gun, it rotates at a constant speed for 2-5 seconds (the dwell time is determined according to the different glaze materials and requirements) to spray the glaze. After spraying the glaze, check the ceramic mug blanks. If there are any areas missing glaze, use a brush or sponge to fill in the glaze. Finally, clean up the excess glaze at the bottom of the blanks to prevent them from sticking to the kiln plate during firing.

2. The difference between spray glazing and dip glazing
Operating method: Glaze spraying relies on equipment for application, while glaze dipping involves directly immersing the green body into glaze slurry to absorb it. In automated production lines, the cost of glaze spraying and glaze dipping lines differs.
Applicable scenarios: Spraying glaze is suitable for complex shapes or partial glazing (such as mugs with transitional colors); dipping glaze is suitable for simple shapes and ceramic mugs with low glaze color requirements. Dipping glaze is highly efficient but not as good as spraying glaze in terms of detail.
Glaze layer effect: Spray glazing can control the thickness of the glaze layer to achieve gradations or textures; dipping glazing produces an even glaze layer but tends to accumulate glaze on the edges.
Cost and difficulty: Spray glazing requires equipment investment and high operating skills; dipping glazing is low in cost and suitable for the production of conventional ceramic mugs.

3. Precautions for spray glazing
The spray glazing process uses a spray gun to apply glaze to ceramic mugs. The glaze slurry has strict requirements. If it is too thick, it will clog the spray gun, and if it is too thin, it will not provide sufficient coverage. In addition, the glaze slurry needs to be stirred regularly to prevent sedimentation. The spray gun needs to be thoroughly cleaned after each use to prevent residual glaze from clogging the spray gun and to prevent residual glaze from being sprayed onto the greenware after drying, causing debris to fall on the ceramic mug. During the glaze spraying process, avoid spraying at a fixed point for a long time (which can easily cause glaze flow). The key is to coordinate the movement speed of the rack with the air pressure of the air gun. Additionally, workers in the spraying workshop must wear masks and goggles to avoid inhaling glaze dust.

4. Preparation before spraying glaze
Body treatment: After drying, the ceramic mug body must be completely cooled, and surface dust must be removed with compressed air.
Glaze Preparation: Adjust the glaze slurry. For specific instructions, please refer to “Instructions for Making Glaze in Ceramic Mugs”
Test spraying: Test spray on scrap clay or bisque-fired pieces to observe glaze adhesion. Adjust the rotation speed and time of the stand, as well as the air pressure of the spray gun.

5. Post-glazing treatment
After spraying the glaze, the raw ceramic mug needs to be dried. During the drying stage, the raw mug should be kept out of direct sunlight or strong winds, and it is best to dry it naturally in the shade for 6-12 hours (depending on the humidity). After applying the glaze, the glazed surface needs to be inspected, mainly to observe whether the glaze is uniform under strong light, with a focus on checking areas prone to leakage, such as the handle connection and the rim of the mug. In addition to inspection, the glaze on the bottom of the mug should be removed so that the part of the ceramic mug that comes into contact with the kiln plate remains free of glaze. Finally, the ceramic mug blanks are placed on the kiln plate with spacing between them and wait to be fired in the kiln.

6. Six major defects that are likely to occur
6.1. Uneven glaze surface
Some substandard colored glazed ceramic mugs have uneven glaze thickness on the surface, which can be distinguished by the naked eye. The orange peel glaze phenomenon of ceramic mugs that we discussed earlier is a relatively obvious example. For the specific causes of this issue, please refer to “Research and Solutions for the Orange Peel Glaze Phenomenon in Ceramic Mugs”  .

6.2. Glaze cracking
After the ceramic mug is glazed and dried, cracks appear. These cracks are mainly divided into horizontal, vertical, and mesh patterns. The main reasons for this are: a. The glaze layer is too thick (>0.5mm) or the glaze has been sprayed multiple times. Because the glaze layer is too thick, cracks are likely to appear on the glaze surface during the drying stage of the ceramic mug. b. The ceramic mug dries too quickly during the glazing and drying stage. The main reasons for this are that the temperature in the drying workshop is too high or there is a strong wind blowing directly on it.

6.3.  Grainy glaze surface
There are obvious bumps on the glaze surface of the ceramic mug. The main reason for this phenomenon is the glaze. The glaze is too coarse, and the particles in the glaze slurry are sprayed onto the ceramic mug. Another reason is that the spray gun is not cleaned regularly, causing the previous glaze to clump together and be sprayed onto the ceramic mug.

6.4. Glaze flow
This phenomenon is similar to the first type of uneven glaze surface. Glaze flow mainly occurs at the bottom and rim of the mug. If we disregard the glaze itself and only consider the glazing process, then local glazing will lead to glaze flow.

6.5. Pinholes/bubbles
Pinhole and bubble defects in ceramic mugs during the glazing process are mainly caused by bubbles and impurities in the glaze, or dust on the greenware.

6.6. Glaze peeling
If the glaze peels off a spray-glazed ceramic mug, there are two possible causes. There are two reasons for this: one is that the green body is contaminated with oil or dust; the other is that the moisture content of the green body is too low. This prevents the glaze from adhering properly to the green body, causing the glaze layer to peel off.

Spray glazing is a process that is often used when customizing ceramic mugs. This process has obvious advantages when dealing with mugs of special shapes and mugs with special requirements for the glaze surface. The essence of good glaze spraying lies in the combination of “standardization” and “refinement.” From raw material selection and glaze preparation to the glazing process, every step is controlled by the people at Xinxiang Ceramics Factory. Xinxiang Ceramics Mug Factory believes that only by converting process parameters into executable SOPs and continuously optimizing every detail can the best balance between efficiency and quality be found.